bennett



Aug. 13, 1 929. c. E. BENNETT l SUPERPOTENTIAL DISCHARGE INSTALLATI-ON Filed Nov'. 25, 1925 3 Sheets-Sheet 1 INVENTOR CHARLES lf. Behave-rr Aug. 13, 1929. c. E. BENNETT 1,724,820

SUPERPOTENTIAL DISCHARGE INSTALLATION Fi'led Nov. 25, 1923 5 Sheets-Sheet 2 4INVENTOR BY f6 JWM M J5 ATToRNEYs C. E. BENNETT l VSUPERPOTEN'IIAL DISGHARGE INSTALLATION Aug. 13, 1929. 1,724,820

Filed Nov. '23, 1923 s sheets-sheet 3 BY J ATTORNEYS Patented Aug. I3, 1929.

UNITED STATES PATENT terrier..

CHARLES E. BENNETT, OF DECATUR, GEORGIA, ASSIGNOR TO BALT MANUFACTR- ING- COMPANY, OF ATLANTA, GEORGIA, A CORPORATION 0F GEORGIA.

SUPERPOTENTIAL DISCHARGE INSTALLATION.

Application led November 23, 1923.

My invention relates to a superpotential discharge installation, particularly valuable for high-tension transmission` lines, but adaptable to various other utilities which will be obvious to those skilled in the art.

Among the more general objectsv of my invention may be mentioned l To provide a discharge installation adapted for a simple hook-up to oney of the Igrounded towers of the usual sub-station layout;

(2) To provide a simple arrester unitadapted for multi-unit installations, and thus readily accommodated to lines of dierent volt-ages by the omission or addition of units -depending upon the normal voltage of the lines in which the installation is made;

(3) To provide an arrester unit having structural characteristics adapting it for installation after the fashion of a suspension or strain insulator.

In the accomlinanying drawingsm Fig. 1 is a more or less diagrammatical elevation of an installation in which may invention is embodied in one form;

Fig. 2 is an enlarged vert-ical section through one of the arrester units shown in Fig. l;

Fig. 3 is a section on the line 3 3, Fig. 2;

Fig. l is a broken elevation illustrative of the connection between a plurality of arrester units;

Fig. 5 is a view similar to Fig. 1, showing a modilied layout;

Fig. 6 is an enlarged vertical section through one of the .arrester units;

Fig. 7 is a. vertical section therethrough;

Fig. 8 is a broken side elevation of a further modification of this typeof unit;

Fig. 9 is another more or less diagrammatic illustration et a further modified. installation;

Fig. l() is an enlarged vertical section through one of the arrester units; land Fig. lllv is a section on the line 11-11, Fig. lO.

In installations of my design now in general use, and known to the trade as the Bennett surge arrester, the construction is such that for lines of different voltages, apparatus of dierent sizes are requisite, or

Serial No. 676,565.

at least advisable, inorder to obtain the best results, although considerable latitude of capacity is obtainable by varying the conductivity of the vaporizable liquid employed in the arrester. This necessitates the construction of many different sizes of apparatus, since arresters are used on lines carrying anywhere from 500 to 150,000 volts. The necessary stock for the manufacture of such a large variety of sizes involves a larger stagment capital outlay and incidental manu* acturing costs than are desirable. Moreover, the arrester tanks used iiorY high voltage lines are quite massive and require separate structural and foundation work for their proper installation. 1

The present invention contemplates a radical departure from this practice in that for suchpa large arrester structure I substitute a small unit, the number of small units being multiplied as required for the protec tion of the line, dependent upon the normal line voltage which the installation is called upon to handle. In the preferred construction which I have shown, each unit has a general structural resemblance to a suspension insulator, and is capable of ready assembly with other units so that a string of arrester units may be readily built up, like a multi-unit insulator.

In the layout shown in Fig. l, the instal-` lationis appropriate for the protection of the transformers at asub-station plant, or the like. rIhe incoming line cable 20 is branched at 2l, the main cable branch 22 leading to the station transformers (not shown), while the ground branch 23 is led through the arrester to the grounded metallic station tower 24 or other suitable support. Interposed in this ground branch connection to the tower is an arc gap 25, preferably adjustable, the spacing of the arcing contacts, such as spheres 26, being such that under normal line conditions no discharge takes place across the gap. rThe gap terminals 26 are carried by arms on independent cable clamps 27 and 28, or the like, which are spaced apart by any suitable insulating means of suiiicient mechanical strength, such as insulators-29. It there should be danger of ieXing between the insulator units 29,

which might disturb the spacing of the gap contacts 26, a single rigid insulator may be substituted therefor, or other means provided for insuring a constant spacing of the cont-acts at a set distance. Between the bracket 28 and the grounded' structure 24 are interposed the arrester units 30 which function to permit the discharge of superpotential on the line, and then promptly interrupt the flow of line current which follows the establishment of an are across the gap 25 by the superpotential.

An arrester unit is'illustrated in Fig. 2. lt comprises a disc-like body 3l of insulating material, provided on its opposite faces with hollow hubs 32, embraced and closed by metallic caps 33, the heads of which form the the end walls of the chambers 34 afforded by the hollow hubs rThe caps are rigidly cemented in position at 35, and carry any suitable means, such as hook 3o and eye 37, for detachable engagement with associated units.

The closed chambers 34 within the hubs of the insulator 3l are placed in communica tion with each other by one or more lower passages 38 through the web or body of the insulator 3l, and also by one or more pass'- ages 39 opening to the upper portions of the chambers. Within the chambers 34 thus afforded is contained a conducting liquid 40, the level of which is here shown to be above the passage 33, but below the passage 39 between the chambers. The liquid may be of any appropriate character, such for example as a water solution of appropriate conductivity for the proper functioning of the arrester. It willvbe noted, of course, that the liquid is in contact with the metal of the caps 33, so that a conducting path through the liquid beween the caps 33 is afforded.

l have shown a string or" four arrester units interposed between the bracket 28 and the station tower 24 in Fig. l. lt will be realized that the number of units is to be varied as needed to aiford the necessary current carrying capacity for the particular voltage of the line in which the arrester is installed. lt is further obvious that a plurality of strings arranged in parallel may be employed, the terminal units of each string being connected to appropriate metallic hangers engaging the bracket 28 and frame 24 respectively.

rlhe particular shape of the insulator body 3l or web which spaces the chambers 34 may be varied in many ways. l have shown a disc-like body, the diameter of which considerably exceeds that of the caps 33 in order to prevent arc-over between the caps. l have also shown the periphery of the web provided with rain-shed ribs 4l to decrease the likelihood of flash-over between the caps 33 during rain storms.

The operation of the appartus is as follows. Under normal line conditions the current flows through the cable -22 to the transformers. On a line disturbance result ing in superpotential, the current arcs across the gap and discharges at once to ground through the arresters and the grounded tower 24. Ordinarily the superpotential is of short duration, and the line is at once relieved. The arc established by the superpotential at the gap 25, however, is maintained by the normal line current and the interrupter then functions. The current passing through the arrester units follows the path from cap to cap 33 of each unit through the liquid in the passage or passages 38 between the chambers 34. The diameter of this passage, or passages, 38 is so predetermined that the heat energy of the current causes the liquid 4() in the passage 38 to vaporize. inasmuch as the chambers 34 are closed, the vapor generated by the current flow places the chambers under pressure, the upper passage 39 serving as an equalizing passage between the two chambers. rlhe current is therefore compelled to pass between the unstable bodies of liquid in the two` chambers and also through vapor under pressure in passage 38 and in the neighborhood of the cold web of the insulator, which is chilled by the liquid. rl'hese conditions are very unfavorable to current'low., and so great a resistance is interposed thereby that the current is interrupted and the are at 25 is dissipated.

As above stated the construction illustrated is more or less diagrammatic, and may be variously modied without departing from my invention. For example, if the character the liquid is such as to be likely to cause the metal caps 33 to deteriorate, the latter may be lrept out of contact with the liquid by providing the interior of the caps Vith a porcelain facing or the like, through which projects a. metallic conductor which will not be injured by the liquid with which it comes in contact.

lt is quite obvious that by appropriate modification of construction the arrester units instead of being arranged horizontally in series, as shown in Fig. l, may be arranged vertically in series. An example of this layout is shown in Fig. 5, in which the line 2O is supported by an insulator string 42 and dead-end tie 43 from the station tower 24. Vertically superposed arrester units are arranged in the ground branch 23 which is suspended at 44. Each unit comprises a cylindrical body 45 of insulating material having intermediate its ends a cross web 46 pierced by the channels 47 and 48 through which communication is established between the end chambers 49 and 50 of the body member. The arrester fluid 40 which is introduced into the chambers fills the passage 47,

while the passage 48 establishes communication between the chambers above the water level for equalizing the vaporpressure.

The metallic caps 51 and 52 which close the ends of the chambers are provided respectively with suspension arms 53 and 54 which project, one above and the other below the insulating body of the unit and terminate in suitable supporting means, such as eyes 55 which lie in the vertical plane of the center of gravity of the unit. Thus, upon the assembly of a group of units hung from 44, as indicated in Fig. 5, the several body members of the arrester units `45 are maintained in a sustantially horizontal position.

Their operation is like that of the units first described. The advantage of this modified arrangement lies in the fact that the arrester is not subjected to the heavy mechanical strains encountered in the construction shown in Fig. 1, and therefore does not need to be of such rugged character. Moreover, in case of failure of one of the arrester units, particularly a failure that is accompanied by physical rupture of the arrester, there is no danger that the incoming line would be dropped, since the dead-end support 42-48 for the line is unaffected. Again, the lead from the arrester units to the tower 24 is so short that should a unit break and the arrester group drop, the lead will support the units out of contact with the main lead 22 to the transformers. Fouling or injury thereto is thus prevented.

In Fig. 8 a further modification of the arrester unit is indicated, the const-ruction being designed to take care of superpotentials above the normal operative capacity of the arrester unit, without injury to the arrester installation. For this purpose the arm 56, extending from the cap 51, is provided beyond the suspension eye 55 `with an up-V wardly directed horn 57 terminating in a sphere 58. The cap 59, at the opposite end of the insulating body of the unit, is provided with an arcing and rain-shield hood 60 overlying the sphere 58, but-spaced therefrom to afford a normally open gap 6l. This construction provides a metallic path (interrupted by short gaps) for the discharge of heavy superpotential (such as direct lightning strokes) which thus bi-passes the normal arrester circuit through the fluid in the arrester units. In other words, the path of the current, if of sufliciently high superpotential, is from cap 59 to cap 59 of adjacent units, across the gaps 61, the interrupted metallic path thus afforded shorting the path through the arrester liquid from cap 59 to the cap 5l of each unit.

Still another construction is indicated in Fig. 9, in which the main 20 is supported as in Fig. 5, from the tower 24 by a group of strain insulators 42. The cable clamp 62 to which the cable and insulator string are connected is provided with an eye 63, from which the string of arrester units is suspended, the ground lead 23 being connected as before to the tower 24. The cable 2O is led from the clamp 62 above the strain insulators 42 to suitable supporting insulators (not shown) and thus to the transformers. In this construction the branch 22 to the transformers is carried above the arrester and out of danger of injury or fouling in case the latter drops upon rupture or failure of one or more units. f

The arrester units are al-so different from those previously described. In this construction the insulating body 64 of the arrester is tubular, and has an associated skirt 65, common in suspension insulators. The vertical chamber 66 within the tubular body 64 is provided with a down leg 67 of considerably less cross sectional area and preferably tapering downward to its lower end, closed by the cap 68. rIhe vaporizing fluid fills the down leg 67 and partially fills the chamber 66. At the upper end of the insulator body 64 is secured a bushing 70 in which is adjustably mounted a conductor rod or electrode 7l, the lower end of which is in current flow association with the liquid 69, while its upper end, projecting above the bushing 70, terminates in an arcing contact 72. The suspension cap 73, secured upon the upper end Qf the insulating body 64, is provided with an inner arcing contact boss 74, which overlies the terminal 72, but is spaced. therefrom.'V

In a construction such as this, a supplemental gap in the ground line is unnecessary, since by properly spacing the contacts 72 and 74 at the head of each unit of the arrester, an equivalent of the usual exposed gap is afforded. That is to say, the arc-over rating of several gaps 75 of the series of arrester units can bev predetermined to a break-down value appropriate to the normal line voltage, so as to prevent a discharge to ground under normal line conditions, but to permit the flow of superpotential to ground across the gaps 75 and through the arreste units. l

The functioning of the apparatus is as follows. When the ground connection is established by superpotential, and arcs are maintained across the several gaps 75 by the line current, the current flow through the liquid in the arrester chambers causes liti ares at 75, and the normal path of the current through 22 to the transformer is restored.

It will be understood that the illustrations are in all cases quite diagrammatic, and that details ot construction may be varied in many ways. In Fig. 9 I have shown a well known type of strain clamp adapted to the installation. It will be understood that a strain clamp provided with arms 27 and 28 is utilized in the layout diagrammatically shown in Fig. l, and also in Fig. 5. Means for lilling and replenishing the liquid in the arrester units may be provided for each or" the several types. As illustrative of an appropriate construction for this purpose, I have shown the cap 52, Fig. 6, provided with a till pipe 7G normally closed by a plug 77. The latter i-s preferably provided with a relief valve which opens when excessive, that is to say structurally dangerous, pressure is generated Within the arrester unit. I have indicated for example, a valve 78 held to its seat by spring 79. Inasmuch as the valve is normally closed there is no danger of loss of liquid by evaporation when the arrester is not in operation, nor even when the arrester functions, unless the pressure created withiril the chamber' is dangerously high. Again, in the construction shown in Fig. l0, the gap 7 5 between the cap boss 74 and the electrode contact 72 may be substituted by a gap between an electrode carried by the cap and the surface of the liquid in chamber 66j Heating of the cap 73 by the play of the are upon the boss 74 is thus avoided.

Tith the understanding that what I claim as my invention is subject to variously modiiied embodiments, I claiml. In a superpotential discharge installation, a string of detaehably connected insu- 1`ttor units, and means alording a current flow path through said string including' vaporizable liquid, the path through the liquid comprising portions adapted to be vaporized by the heat energy of the current flow therethrough.

2. In asuperpotential discharge installation, a string ot detachably connected insulator units, and means affording a conducting path through each unit of said string andincluding a vaporizable liquid, the path through the liquid ot each unit comprising an area adapted to be vaporized by the heat energy of the current flow therethrough.

3. In a superpotential discharge installation, a suspension insulator having spaced metallic suspension members, and means affording a conducting path between said members comprising liquid adapted to be vaporized by the current flow therethrough.

4. In a superpotential discharge installation, a chamber-ed suspension insulator having spaced metallic suspension members, and means of allording a conducting path between said suspension members including a vaporizable liquid in the chamber of the insul'ator.

5. In a supernotential discharge installation, a suspension insulator comprising a body of insulating material chambered to form a liquid container having portions of different cross sectional area occupied by liquid, and metallic suspension caps in current flow association with the liquid on opposite sides of the area of reduced cross section.

6. rlfhe combination with a power cable, of a structure to which the cable is connected vfor support, and a suspended, superpotential ground connection having a vaporizable liquid in the path of the current tlow to ground.

7. The combination with a power cable, of a structure to which the cable is connected for support, and a suspended, superpotential ground eonnection having a vaporizable liquid in the path of the current flow to ground, and gap contacts in series with said liquid.

8. A grounded structure, means for suspending a power cable from said structure, a suspended, gap-interrupted electrical connection between said cable and grounded structure, and means in said connection for interrupting the iiow of current.

9. A grounded structure, means for suspending a power cable from said structure, a suspended, Agap-interrupted electrical connection between said cable and grounded structure, and means in said connection i'or interrupting the flow of current, said means comprising a vaporizable liquid forming portion n of the current path to the grounded structure.

10. A grounded structure, means -for suspending a power cable from said structure, a suspended, gap-interrupted electrical connection between said cable and grounded structure, and means in said connection for interrupting the flow of current, said means comprising a series of independent bodies ot vaporizable liquid forming portion of the current path t0 the grounded structure.

In testimony whereof I have signed my name to this specification.

CHARLES E. BENNETT. 

